Bushed transformer terminal



May 26, 1942.

E. M. MEYER BUSHED TRANSFORMER TERMINAL Filed Nov. 3, 1959 Patented May 26, 1942 UNITED STATES PATENT OFFICE Edwin M. Meyer, Parkersburg, W. Va., assignor to Porcelain Products, Inc., Findlay, Ohio, a corperation of Delaware Application November 3, 1939, Serial No. 302,767

3 Claims.

This invention relates to improvements in the insulated terminals of transformers, capacitors and similar equipment wherein high tension current is transmitted between a closed container or tank and the transmission line, a supply circult or a distributing circuit. The principal problem is to provide for a conducting path for the current through an opening in a, metallic container properly sealed against moisture, gases or dust particles. Equipment of this type requires an adequate sealing between the insulating member and the supporting receptacle or tank. Since such insulating members are usually made of rigid porcelain, the severe stresses evenly.

A further object of my invention is to increase the extent of the sealing contact between the bushing and the plate upon which it is mounted.

Another object of my invention is to assemble be connected and disconnected without disturbing the sealed condition of the bushing.

The following description will suggest otherobjects incidentally obtained by this invention. As illustrative of the invention I have shown in the accompanying drawing the preferred embodiment of the invention. In the drawing,

Fig. 1 is a side elevation of the bushed terminal, some portions being indicated in vertical section;

bushing 6 mounted upon the cover plate 1 of a tank or other receptacle and in turn carrying the hooded cap nut 8 by which the conductor in the tank is connected to the outer line cable.

The bushing 6 is a hollow tubular piece of glazed porcelain of satisfactory insulating characteristics. The upper portion .of the bushing has a series of porcelain ribs or petticoats 8. The lowermost petticoat 9 forms a shoulder l0 running completely around the bushing. This shoulder IE! is separated from the main body of the bushing by a circular groove H. A ring of insulating material 12 fits below the shoulder l0 and forms a seal between it and the cover created by the pressure of tightening the sealing plate I. The cover plate has an up-turned cirmembers often results in damage to the porcecular lip l3 of a diameter less than that of the lain, distortion of the cover plates and frequentshoulder I0 so that the lip comes opposite the 1y an imperfect seal. It is an object of my ingroove H. A gasket I4 held in the groove ll vention to avoid abnormal stress concentration rests upon the edge of the lip l3 and thus proby eliminating sharp angles of the porcelain but vides a second or additional sealing means at this placing the latter in pure tension free from bendpoint. The thickness of the gaskets I2 and I4 ing thus increasing the ultimate strength of the is such that they are simultaneously compressed porcelain. with substantially equal pressure thus equalizing A further object of my invention is to provide the compression upon the shoulder l0 and groove improved means for clamping the porcelain. H and also increasing the area of sealing con- Thus I use a clamp of ductile or deformable tact. metal which will under the pressure applied, con- The lower end of the bushing 6 is in the form form more closely to the adjacent surface of the of an extension I5 having an intermediate flarbushing, increase the area through which presing portion [6. This flaring or tapering portion sure is applied and distribute this pressure more 30 forms an extended conical seat for the clamp.

In order to equalize the pressure of the clamping action and to distribute it uniformly around the porcelain bushing I use a segmental clamp I1. This clamp is formed of three identical segments l8 shown more particularly in Fig. 3. The inner walls I9 of these segments form a continuous conical wall having a taper or flare corresponding to that of the wall I 6 on the bushing. Each end .of each section is cut away for 0 half of its depth as indicated on the drawing.

The outer lug 20 is provided upon the end farthest from the axis while the inner lug 2| is borne from the portion remaining nearer the axis. The lug 20 is tapped with a plain hole 22. The inner lug 2| has a screw-threaded opening 23. The diameter of the opening 22 is slightly in excess of the diameter of the opening 23.

Adjustment screws 24 pass through the plain hole 22 of one lug 20 and are threaded through Fig. 2 is a cross-section on the line 2--2 of the hole 23 in the adjacent lug 2|. Beyond the Fig. 1 in the direction indicated by the arrows lug 21 the bolt 24 is brought up against the lower and face of the plate I and opposite the shoulder Fig. 3 is a perspective view of a segmental colill and sealing gasket l2. lar. Each bolt 24 has a lock nut 25 bearing against Generally speaking the terminal consists of a the lug 20. The bolts 24 are advanced uniformly to bring the clamping collar tightly against the sloping Wall IS. The segments I8 of the collar are made of soft or deformable metal such that any inequality of contact will be compensated for by slight change in form of the metal thus providing a substantially uniform area of contact and pressure. against the sloping wall l6. While I have shown three bolts 24 as pressing against the plate I, this number may be increased where found desirable. However, the provision of two sealing gaskets l2 and I4 will provide adequate seal without multiplying the number of pressure points against the plate I.

The bushing 6 has an axial passageway 26 running from end to end. This passageway is intended to receive a cable terminal at its upper end. A cap-nut 36 is provided with a lower portion flared outwardly to form a cap 38 of suiiicient size to extend beyond the end of the bushing 6. The cap-nut is made of suitable cast metal and formed on one side of its central axis with an enlargement. This enlargement has a vertical opening 42 parallel to the longitudinal axis of the cap-nut. Set screws 43 threaded in the side of theenlargement serve to clamp the end of the cable or other conductor 44 within the opening 42. i

The above described device needs little explanation as to its assembly or'use. The bushing .6 .is mounted upon the plate 1 with the gaskets l2 and I4 forming continuous seals between the lower petticoat 9 and the plate I. The segments l8 of the clamp I! are placed around the smaller diameter of the sloping wall l6 and the bolts 24 pass successively through the lugs 20 and 2| and the ends of the bolts brought against the plate 1 opposite the shoulder l0. Tightening these bolts brings an evenly distributed compression against an extended area of sloping walls l6 providing for a tight seal without unduly straining the porcelain.

By the provision of the device as just described an extremelyefficient bushed terminal is provided for a closed receptacle. The bushing is well sealed around the aperture in the tank. At the same time the pressure is'applied evenly at the sealing edges by means of a clamp which is best suited for compression in the porcelain bushing itself. The compression surface is in the form of a, cone of considerable area which receives the pressure uniformly throughout. The porcelain is put under simple tension and thus best adapted for satisfactory use.

While the novelty of the arrangement is apparent in the device when taken as a whole, still the several parts are individually novel as well. While I have shown a typical and the preferred form of the invention it is to be understood that the form, proportions and minor details may be varied widely without departing from the scope of the invention as stated in the appended claims.

What I claim is:

1. In combination with a cover plate having an opening with an upturned lip, a bushing having a peripheral shoulder with a groove opposite the lip on the plate, sealing means between said shoulder and plate and separate sealing means between said groove and lip, a conically flaring extension on the bushing, a segmental collar having a' conical inner wall in extended contact with the extension and means carried by said collar for pressing against the plate on the side opposite the sealing means.

2, In a device of the class described, a multiple segment collar with a circular inner wall having a conical tapering slope, said segments having interfitting end sections, one end section of each segment being screw-threaded, the other end section being bored and adjusting screws passed through the end sections of adjacent segments.

3. In a device of the class described, a multiple segment collar with a circular inner wall I having a conical tapering slope, said segments having overlapping end sections, one end section of each segment being screw-threaded, the

other end section being bored, and adjustingscrews passed transversely through the end sections of adjacent segments.

EDWIN M. MEYER. 

